Study Group — Characters & Cast

To achieve high enough grades to enter a four-year college and make his mother proud; evolves into protecting his study group members at all costs.

Begins as an academically hopeless student hiding his legendary fighting skills to avoid trouble. Over the series, he learns to embrace his physical strength not as a flaw, but as a righteous tool to protect his friends' right to study, gradually gaining confidence and leadership.

To reform Yusung Technical High School and honor her late colleague's legacy.

Starts as a temporary teacher attempting to uncover the truth behind a past teacher's murder while helping Ga-min. She transforms from an isolated investigator into a protective pillar for the entire study group, risking her career to expose school corruption.

Maintaining absolute control over the school and fulfilling his crime-boss father's dark expectations.

Entrenched at the top of Yusung Tech's violence hierarchy with ties to the syndicate Yeonbaek Gang, Han-wool believes power and money dictate everything. As Ga-min continuously dismantles his reign, his smug composure dissolves into desperate, violent obsession.

Surviving high school quietly; evolves into actively helping his friends pass their exams and fighting back against abusers.

Initially defeated by poverty and relentless bullying from upperclassmen, Se-hyun hides his sharp intellect. Joining Ga-min's study group restores his self-worth, transforming him into the strategic brain of the group.

Protecting her vulnerable twin brother Lee Hyun-woo; evolves into fighting for the study group’s collective future.

Begins as a defensive, hardened student protecting her twin brother from bullies. Joining the study group softens her emotional exterior, letting her build genuine, trusting friendships.